This invention relates to the manufacture of electric lamps and, in particular, to an accumulator for temporarily storing either bulbs or finished lamps prior to the next manufacturing operation.
In any manufacturing operation, it is desired that the machine performing the manufacturing steps have an adequate supply of parts at hand in order to achieve maximum utilization of the machine. In the specific case of the manufacture of electric lamps, an automatic lamp manufacturing machine group requires that an adequate supply of bulbs be available to the sealing turret, where the bulb and mount are joined and sealed.
Present supply systems are encumbered by jams and breakdowns causing gaps in the bulb supply. Present linear or in-line accumulators convey the bulbs hanging cullet-down between two parallel belts. The bulbs accumulate by simply being forced against one another at the outfeed end of the accumulator. This is hard on the bulbs since they are forced together by the belts, causing jams and breakage, and limits these devices to fewer bulbs than desired.
For larger capacity, circular accumulators are added in which the bulbs are held between a spiral track and a rotating drum. This causes additional breakage due to the rotation of the bulbs. Where the bulbs accumulate, the touching surfaces on adjacent bulbs are moving in opposite directions, causing possible scoring, and a consequent weakening, of the bulb. This may result in immediate breakage or, worse, breakage in the sealing turret due to thermal stress. Additional breakage may be caused by the higher bulb-to-bulb pressure. Since broken glass falls down on good bulbs from the tiers above, damage to good bulbs may result as well as jam-ups. This type of accumulator rotates relatively slowly and has a relatively large recovery time, i.e., the time it takes for a bulb to travel from the infeed end to the escapement when the accumulator is empty.
Accumulators of the prior art typically employ gate-type escapement mechanism for metering the bulbs on the outfeed end of the accumulator. This type of release jars the bulbs with repeated impacts since the bulbs are forced forward by the conveyor belts, causing further breakage and jamming.
In general, bulb accumulators of the prior art are characterized by high bulb-to-blub contact pressure and abrupt handling of the bulbs.
There is thus a need to be able to temporarily store or accumulate bulbs near the sealing turret and to feed them at a uniform rate even though the bulb supply to the accumulator contains gaps. There is also a need to accumulate the bulbs as gently as possible. It is also desired that the bulb makeup or recovery time be kept to a minimum.